This is an investigation of the effects of chronic malnutrition on social, cognitive, and affective behavioral development of children. Six and seven year old children, identified as chronically malnourished, will be provided daily protein and calorie supplements. Children from experimental groups receive food supplements for two consecutive 14 months periods; children from control groups receive supplements beginning in the second intervention period. The criterion behaviors include attentional capacity, memory, and problem-solving; emotional responsivity and impulse-control; and patterns of social interaction. Periodic assessments of health and nutritional status are made. Differential effects of food supplement on children not malnourished will also be determined.